1. Field of the Invention
The invention provides a method for identification of traffic lane boundary, particularly a method for identification of traffic lane boundary by applying the frequency span information and the probability density function model.
2. Description of the Prior Art
When the radar microwave detector is used to count the number of vehicles of every lane in multiple lanes at the same time, it has to set up the information of lane boundary first. It is a real difficult job. The main reason is that when the vehicles pass through different lanes, it is unable to distinguish lane boundary accurately to obtain the vehicle information on every lane, due to the reflection of microwave generated by near the adjacent lanes.
As the provided prior art for the other radar microwave technology application to the identification of traffic lane, in US Patent No. US2007/0016359A1 “Method and Apparatus for Providing Automatic Lane Calibration in a Traffic Sensor”, Canadian EIS Company provides the central frequency of every lane, and assumed about five-meter width lane to conduct the upgrade and setup. The input is by using the displacement of a vehicle. The calculation of displacement is to calculate the distance between the central frequency of closest lane and a certain representative position, in order to modify the central frequency of lane constantly. However, the lane width is already been fixed in the technology. Due to the traffic lane being fixed, there is no more flexible calculation for lane width, so that it is still difficult for the practical application.
In addition, in U.S. Pat. No. 6,556,916B2 “System and Method for Identification of Traffic Lane Positions”, the boundary of each lane is provided. After each car passing through, the appearance position having the most representative frequency of car plus 1 will be selected as the input. The accumulated figure is utilized for the learning of Gaussian Mixture Model, and the valley of learning is used as the lane boundary. The position of single point is used to represent the position of vehicle in the invention. It may cause a larger error in calculation, so that there is also a difficulty for the practical application.
Thus, in various conventional technologies for the radar identification of traffic lane, there are various shortcomings such as inaccuracy and lack of flexibility, and there are not suitable for the practical calculation of lane boundary. In order to respond the demand, it is necessary to develop the relevant technologies for identification of traffic lane positions, so as to save the cost such as manpower and time etc. and be able to obtain the correct lane width.